1. Field of the Invention
The present invention relates to a hydraulic motor or pump, comprising a first and a second body which in association with definitive boundaries limits an annular cavity with a constant cross-section opening in relation to the centre of the annular cavity, where the first body is static and the second body is rotatable, or vice versa, and where the annular cavity is connected with passages respectively to a hydraulic pressure side and a pressure neutral side, and where the first and the second body comprises evenly spaced radial projecting protrusions which connects the bodies and divides up the annular cavity in a number of chambers which alternately are put on hydraulic pressure and are pressure neutral.
2. Description of Related Art
Such a device is disclosed in French Patent FR 1 540 472 where pressurizing of the chambers in the annular cavity takes place via respective passages to a hydraulic pressure side and a pressure neutral side, by star-shaped spring held valves in the static part, which forms semi-static separations between pressurized chambers and chambers with neutral hydraulic pressure, and where the protrusions on the rotatable body during rotation passes the star-shaped valves rotating the star-shaped spring held valves, which respectively opens and closes the passages to the pressurized side and the pressure neutral side. In the same publication is further shown an embodiment of the device suited for one direction of rotation for the rotatable body, wherein the star-shaped valves are substituted by displaceable sliders. The device is in a manner that if the number of radial outstanding protrusions on the rotor is n, then the number of star-shaped, rotatable mounted valves or sliders will be (n+1).
However, this device shows several drawbacks of which should be mentioned, that the hydro-mechanical losses associated with the friction between the moving mechanical parts is expected to be relative considerable with respect to the embodiment comprising the star-shaped valves. Further, the embodiment comprising the displaceable sliders allows only rotation of the rotor in one direction of rotation, due to the design of the sliders, which limits the abilities of use for this embodiment of the device. The device thus is not suited for macro structures such as yaw motors in windmills, where relatively large torque is required, and that rotation can be implemented in both directions of rotation.